Cold rolling aluminum and product



y 5, 1955 J. D. DOWD ETAL COLD ROLLING ALUMINUM AND PRODUCT HVVENTDRS James D. Dowd 9- y Alber? A. Perrier ATTORNEY 2 Sheets-Sheet l GEAR Luz mwbgkg. 5 Q Wm E Q H Utah Filed June 27, 1963 J. D. DOWD ETAL COLD ROLLING ALUMINUM AND PRODUCT July 6, 1965 2 Sheets-Sheet 2 Filed June 27, 1963 INVENTORS James D. Dowd y Alberf A. Perrier @Lai ikz'tzz ATTORNEY m c States at i I Ic 6, r a

adjacent areas of the strip surface as it passes through the mill rolls. Whether the explanation of these non- C'IEILD RtBLLING ALUM'ENUM AND PRQDUQT Sames ll). Dowd, New Kensingtou, Pa, and Albert A.

ierrier, Maryville, Tenn, assiguors to Aluminum Zornpany of America, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 27, 1953, Ser. No. 291,145 6 Claims. (til. 72-45) This invention relates to methods of cold rolling aluminum sheet in strip form wherein a water base rolling lubricant is used, and to cold rolled aluminum products of such methods. As generally used herein, the word aluminum includes both aluminum in its various grades as to purity and wrought aluminum base alloys, alloys which usually contain at least 85 percent aluminum. For many years the most rapid cold rolling of aluminum sheet in strip form has been accomplished by the use of multistand mills of various types. Sometimes this rolling is referred to as continuous cold rolling or tandem rolling, but essentially it consists in engaging the metal in a multistand mill, to be cold reduced successively by two or more stands of rolling mills placed in line, whether the rolling mills used be backed up mills (such as, for instance, the 4-high type of mill) or unbaclred mills (2- high mills). The rate at which the heat generated in these mills during the cold rolling could be removed has been, in the last analysis, controlled by the cooling efiiciency of the rolling lubricants. Mineral oil lubricants have to date been the only ones tolerable in the rapid commercial cold strip rolling of aluminum. Commercial aluminum sheet, i.e. sheet of commercial acceptability from the standpoint of flatness and surface regularity, is not producible .in a commercial way in multi-stand rolling if either the percent reduction being made or the speed at which that reduction is made creates a heat problem that is not controllable by the rolling lubricant employed. Such problems do persist regardless of the volurne of lubricant employed, since the lubricant is effective as a coolant only at localized areas of application. As generally distinguished from other metals, the cold rolling of aluminum sheet has heretofore for most purposes been efiected by the use of rolling lubricants of a mineral oil base (such as mineral oils free of water, and with or without eX- treme pressure additives). The reason for the use of a mineral oil base, instead of a more effective coolant, namely a water base lubricant (such as oil-in-water emulsions which are commonly employed in cold rolling other metals), has been that when Water is used in the cold reduction of aluminum a tendency to water stain inevitably appears and, in addition, surface non-uniformities are encountered. Water-staining of aluminum strip or sheet ordinarily occurs in a short period of time if water is permitted to remain in contact with it, and is usually charac terized by white or gray spots appearing on the sheet surfaces, making the sheet commercially unacceptable for many purposes. The surface non-uniformity referred to is that in which the surface exhibits small, localized differences in color or appearance, differences apparently resulting from small, localized variations in sheet reduction. Such surface non-uniformities, sometimes called lacerations, reflect the localized tearing of the surface that is perhaps caused by diiferences in effective lubrication of uniformities be a proper one or not, they are objectionable differences in color or appearance not caused by water staining but by unequal surface treatment occuring during rolling.

The general object of the invention is to provide methods for the production of aluminum sheet which is commercially acceptable as to surface, methods which will permit the satisfactory use of a water base rolling lubricant and thereby increase the capacity of known rolling equipment to effect reductions in aluminum strip at higher volumes per unit of time. These methods permit the production of cold rolled aluminum sheet, in the aforesaid manner, that has substantially uniform, smooth surfaces, substantially free from surface non-uniformities, and substantially free from water stain or the tendency to water stain by reason of retained water.

The invention will be described in connection with the accompanying drawings in which:

FIG. 1 is a diagrammatic side view of a four stand continuous 4-high mill in which the invention may be employed;

FIG. 2 is a diagrammatic top view of the strip leaving a mill stand and having water base rolling lubricant reapplied thereto;

FIG. 3 is a diagrammatic top view of'the strip and air jets applied thereto as the strip leaves the final mill stand;

FIG. 4 is a side view, on a larger scale, of the strip, air jets and associated exhaust ducts near the exit side of the final mill stand; and

FIG. 5 is a side view of the strip, air headers and associated exhaust ducts beyond the exit side of the final mill stand.

In considering the drawings and the following description of the invention, it may be noted that the invention is described in connection with a four stand continuous 4- high mill as shown in the drawings, a type of mill which may conveniently be used for the rapid reduction of aluminum strip, but other mills placed in tandem, whether backed up or unbacked, and whether of more or less than 4 mill stands, may also be used.

Referring to FIG. 1, an unwinding coil 1 of aluminum strip 2 is supported by a cone unwind 3, which may be provided with a brake or drag generator. The strip 2 is fed from coil 1 over a hilly roll 4 through a multiple roll bridle 5, and into the first mill stand (stand 1). This mill stand has work rolls 6 supported by backing rolls 7. Roll and strip coolant sprays 8 at the entry side of the mill stand desirably direct rollinglubricant which may be an oil-in-water emulsion, toward the nip of the work rolls 6, onto both upper and lower surfaces of the strip, and also desirably onto the work rolls above and below the nip of the work rolls and toward the lines of contact of work rolls 6 and backing rolls 7. The volume of rolling lubricant so sprayed may be regulated by providing a plurality of spray sections 8 across the faces of the rolls, i.e. across the width of strip being rolled, for control of roll shape and sheet flatness.

Passing out of the first mill stand, the strip 2 desirably passes over a tension roll 11 near the center of the span between the successive mill stands, through a bridle 12 located near the entry side of the second mill stand (stand 2) and into the second mill stand. In order to minimize carry over and splashing of rolling lubricant from the top U backing rolls 7 onto the top of strip 2, a splash guard 13 is applied to the exit side of that roll to collectand carry rolling lubricant to the sides of the mill.

As the strip passes out of the first mill stand its surfaces are then relatively dry, i.e. substantially free of water, although it retains some oily lubricant on its surfaces. In accordance with the invention, desirably the top surface and preferably both surfaces of strip 2 exiting from this first mill stand are provided immediately with a substantially uniform coating of rolling lubricant applied by rolling lubricant sprays 15, 16 and 17. Sprays 15 are the top sheet sprays, located above the strip 2, between the first mill stand and tension roll 11. Sprays 16 and 17 are the bottom sheet sprays, located below strip 2, preferably positioned just before and after the tension roll 11, respectively. These sheet sprays 15, 16 and 17 apply an amount of rolling lubricant providing a substantially uniform spray coating pattern of rolling lubricant droplets across the width of the strip 2, indicated by the pattern 19 for sprays 35 in FIG. 2. They produce a substantially uniform coating of rolling lubricant on the surfaces of that portion of the strip exiting from the immediately preceding mill stand and passing the spray location nearer the preceding mill stand than the following mill stand. They are pref erably used, as indicated, to apply the rolling lubricant coating, and thus applying a substantially uniform amount of oily lubricant directly upon the strip surfaces promptly upon the strips leaving the preceding mill stand, Without flooding the strip and hiding its appearance and shape from the operator.

Roll and strip coolant sprays 18 are applied at the entry side of the second mill stand in a manner similar to the way the corresponding sprays 8 are applied at the entry side of the first mill stand. Some flow, splash-and splatter of rolling lubricant from these sprays 18 inevitably finds its way back on the bridle rolls (if a bridle 12 is employed, which is optional), and also tends to be deposited further back on the strip 2. However, the previous substantially uniform coating of the strip 2 with rolling lubricant, by top sheet sprays 15 in particular, but also desirably the bottom sheet sprays 16 and 17, minimizes the tendency of any such flow, splash or splatter of rolling lubricant or other water, oil or grease to cause non-uniform effective lubrication of the strip entering the second mill stand.

The passage of strip 2 out of the second mill stand and into the. third mill stand is similar to its passage between the two preceding mill stands. A backing roll splash guard 23 is desirably employed. Further, air jets 24 are desirably employed on the exit side of the second mill stand, being directed against the line of contact of top work roll 6 and top backing roll 7 at each side of strip 2 to blow rolling lubricant reaching these locations toward the sides of the mill. Rolling lubricant sprays 25, 26 and 27 are preferably employed for the reasons previously stated, and a tension roll 21 is usually employed. A bridle may be employed, but only one roll 22 is shown. Roll and strip coolant sprays 28 are employed at the entry side of the rolls of the third mill stand in the manner previously indicated.

Similarly, the strip 2 passes to the fourth mill stand, desirably over a tension roll 31. Backing. roll splash guard 33 and air jets 34 are desirably employed as previously indicated. A top bridle roll 32 may be used to determine the pass line of the strip entering the fourth mill stand if desired. Rolling lubricant sprays 35, 36 and 37 are employed for the reasonspreviously stated, and roll and strip coolant sprays 38 are employed in the manner previously indicated. The pattern 19 of rolling lubricant applied on the top surface of the strip 2 by the rolling lubricant sprays 35, for example, is shown diagrammatically in FIG. 2.

The handling and treatment of strip 2 as it exits from the final mill stand is somewhat different from that described in connection with the other mill stands. In this connection FIGS. 3, 4 and 5 should also be referred to, in

addition to FIG. 1. As shown in these figures, the strip 2 preferably passes under a hold down roll 50 and over a billy roll 60, and is wound up as a coil 61 on a rewind reel 62.

A top work roll and top backing roll splash guard 43 and drain gutter, on the exit side of the last mill stand, are desirably employed. It is similar to the splash guards 13, 23 and 33 applied to the top backing rolls on the other mill stands, but desirably extends down to the top work roll face at this location. As in the case of the other stands, the surfaces of the strip 2 as it exits from the last mill stand, over most of their extent, are dry except for oily lubricant remaining on such surfaces. However, there is a tendency for a head of the water base rolling lubricant to pass through the rolls at the edges of strip 2, providing one source of now undesired water on the strip. In order to remove this water base rolling lubricant from the edges and side portions of the surfaces of the strip, a plurality of air jets 41 are directed toward the strip and the nip of the rolls on the exit side, both above and below the strip 2, at either side of the center line of the mill. These air jets 41 blow slightly down on the sheet and toward the rolls, as seen in the side views of FIGS. 1 and 4. They blow slightly toward the sides of the strip (ends of the rolls), as seen in the plan view of FIG. 3. Thus, they blow water base rolling lubricant and any free water off the sides of the strip and toward the sides of the mill. The number of air jets 41 that are energized on either side is determined by the width of the strip being rolled. In order that emulsion and water so removed does not remain near the strip 2 where it may .re-deposit on it, exhaust ducts 42 are provided at each side of the mill, with openings toward the rolls and the edges of the strip 2, near the exit side of the rolls. The exhaust ducts 42 may be connected to a suitable exhaust system to collect and withdraw air blown across the strip, together with emulsion and water entrained therewith. Squeegee rolls or rubber wipers could also be used to remove moisture from the exiting strip, but are less desirable because of their tendency to wear and scratch the surfaces of the strip.

Further, despite all efforts to keep the strip 2 essentially dry as it leaves mill stand 40, there is almost inevitably some re-deposit of wall base rolling lubricant on the surfaces of strip 2, especially the top surface, as it passes toward the rewind reel 62. It has been found that such deposits, if not excessive, can advantageously be removed with the devices shown more clearly in FIG. 5. The device effective on the top surface of the strip 2 is the air header 44 which directs a thin sheet of dry air across the width of the strip 2 and almost normal to the strip 2, but inclined slightly toward the mill rolls and away from the rewind reel 62. A slot 45 in the air header 44 produces the sheet of air, and this slot is desirably adjustable about a nominal slot width of about .015 inch. The edges of the slot 44 in air header 45 are desirably adjustable to a position about .010 inch above the top surface of the strip 2 as it passes over billy roll 60. The billy roll is conveniently provided with a cleaning buff 59. On the side of the air header 44 toward the mill stand, and also just above the strip 2, an exhaust duct 46, open toward the air header 44, is desirably provided to collect and withdraw air blown across the strip by the air header 44, together with emulsion and water entrained therewith. This further tends to avoid having emulsion and water re-deposit on the strip 2. The exhaust duct 46 may be connected to a suitable exhaust system.

While not necessarily required, the similar application of air header 54 to direct dry air through slot 55 onto the under surface of strip 2 may be usefully employed in some cases. In the form illustrated, the strip surface clevation is determined by the strip passing under the hold down roller 50, which may be provided with a cleaning buff 49. The slot 55 in air header 54 is desirably spaced from and oriented to the bottom surface of the strip 2 in a manner similar to the way slot 45 is spaced from and oriented to the top surface of the strip 2. An exhaust duct 56 is also desirably provided adjacent the line of impingement of air from slot 55.

By the use of the top air jets 41, and air header 44, particularly when used in association with exhaust ducts 42 and 46, the top of the exiting strip 2 may be kept substantially free of emulsion except for residual oily lubricant remaining on the surface. Keeping the bottom of strip 2 essentially dry is not as difiicult, but may be better assured by the similar use of bottom air jets 4i and air header 54, particularly when used with exhaust ducts 42 and 56. Using such devices, particularly for the top surface, aluminum strip cold rolled with a water base rolling lubricant may be rewound into a coil 61 without having its surfaces contaminated with water causing water stain of the aluminum strip, or tendency to water stain by reason of retained Water. That is to say, the surfaces are so free of water staining that the product is acceptable for commercial purposes.

In the foregoing general description of the manipulative aspects of the invention as applied to a four stand continuous mill, it is to be noted that the most critical locations in respect of the processing of the strip through the mill are (l) the span between the next to the last mill stand and the final mill stand and (2) the span of the strip passing out of the final mill stand, egg. to the rewinding coil. It has been observed that the most important factor in producing a substantially uniform, smooth top sheet surface is the substantially uniform application to the top surface of the strip of a uniform coating of Water base rolling lubricant at a location just out of the preceding mill stand, prior to its passage to the final mill stand. Likewise, it has been found that the important factor in producing sheet substantially free from water stain, or tendency to water stain by reason of retained water, is the substantial removal of emulsion from the top and edge surfaces of the strip as it leaves the final mill stand. In other words, the treatment of the strip prior to entry into the stand or stands preceding the final mill stand is not as important, although the similar treatment of the strip at such locations, as described herein, is often desirable. Further, the treatment of the bottom surface of the strip is usually not as important, since it is not as exposed to irregular deposit of rolling lubricant between mill stands, and will tend to remain free of rolling emulsion beyond the final mill stand, although the similar treatment of that surfaces, as described herein, is often desirable.

As an example of the mill structure, a four stand continuous 4-high mill, arranged as described, may have roll stands with working rolls 18 inches in diameter and 44 inches long, and with backing rolls 46 inches in diameter and 44 inches long. Such a mill hase been employed for the cold rolling of aluminum strip in accordance with the invention, in rolling widths of about 24 to about 39 inches, typically 36 inches. Sheet thicknesses out of the final mill stand may conveniently range from .006 to .050 inch, and the more difiicultly obaiued thicknesses of .006 to .016 are readily obtained by the practice of the invention. The large reductions described below have been made on various aluminum sheet products rolled in strip form, using such a mill and an oil-in-water emulsion as the water base roll and strip lubricant and coolant. A typical rolling lubricant emulsion used is a dispersion in Water of about 12 percent of oil providing the oily lubricant for rolling. This oil, sometimes referred to as the neat oil (prior to its dispersion in water), may comprise a mineral and polybutene oil base, fatty acid, and emulsifier and coupling agents. When dispersed in water, with a water content of about 88 percent, an emulsion is produced which is both a good roll and strip coolant and a source of oily lubricant for the rolls and strip.

Typical aluminum products rolled in strip form in ac- Nominal composition in per cent (remainder A1 and Aluminum alloy usual impurities) Mn Mg Or (Al of commercial purity) The tabulated 5000 series alloys, and the alloy last listed, exemplify alloys containing 2 to 5 percent magnesium as the principal alloying constituent, and are among the stronger, work-hardening alloys of aluminum, alloys which are much more difficult to roll than the commercidly pure metal. Alloys 5052, 5155, 5086, and the 4.5% Mg alloy have also been rolled in two-side clad strip form, i.e. as a core alloy constituting at least 90 percent of the thickness, with analuminum metal cladding liner on each surface, each constituting at least 2 to about 5, typically 3, percent of the strip thickness. In the case of 5052 and 5086 alloys a typical cladding is 3003 alloy, and in the case of 5155 alloy and the 4.5% Mg alloy, a typical cladding metal is 1100 aluminum. These cladding metal layers may desirably be any of the metals selected from the group consisting of aluminum and aluminum alloys, particularly those free of more than 0.05 percent magnesium.

Alloy 5052 strip, supplied in the annealed condition at a thickness of .110 inch, and widths of about 36 inches, has been cold rolled in accordance with the invention, at finishing speeds in excess of 1500 feet per minute, according to the following schedule of reductions:

Percent re duction (total) Percent re duction (per stand) Stand Reduction Percent reduction (per stand) Percent reduction (total) Stand Reduction The resulting sheet products are in an extra hard (Hl9) temper.

Alloy 5086 strip, supplied in the annealed condition at thicknesses of .110 inch and .090 inch, in widths of about 36 inches, has been cold rolled in accordance with 5 the invention, at finishing speeds in excess of 1200 and 1500 feet per minute, respectively, according to the following schedules of reductions:

The resulting sheet products, in the two cases tabulated immediately above, are in an extra hard temper designated 5086-1-119, and have typical as-rolled tensile ultimate strengths of 61,000 psi. Conventional full hard 5086- Hl8 which has a typical tensile strength of 57,000 p.s.i., is obtained in conventional rolling practices With total reductions of less than about 80 percent.

In rolling these and other aluminum sheet products as described, it has been found possible to obtain commercially flat, smooth strip, while making the indicated reductions, at the indicated speeds when using a water base rolling lubricant. The critical final mill stand reduction, it will be observed, is made in the above practices on strip that has already been reduced more than 80 percent in thickness by the preceding stands, i.e. is made on hard rolled strip. Yet a further substantial reduction in excess of 20 percent is made in the final mill pass, bringing the total reduction to more than 85 percent (or a strip elongation of more than 7 to l), and even over 90 percent (or a strip elongation more than 10 to 1). Lighter total reductions, say of 65 percent or more, may also be advantageously taken. Despite such heavy reductions being made, it has been found that strip surface irregularities, including the non-uniformities previously mentioned, are substantially avoided when at least the top surface of the strip, at least between the immediately preceding and final mill stands, is provided with a substantially uniform coating of the water base rolling lubricant prior to exposure thereof to any irregular deposition of the lubricant from the sprays or rolls of the final mill stand. It has been observed that providing a substantially uniform coating pattern of the water base rolling lubricant appears to permit a uniform amount of oily lubricant to be deposited on the strip surface from the water base lubricant coating emulsion. This deposition appears to take place during the uniform, finite time in the travel of the strip from the zone of spray application, near the preceding mill stand, to its entry into the following mill stand. However, it is not intended that the invention be considered limited by this tentative explanation of the mechanism involved. In any event it has been found that the cold rolling of strip having a commercially acceptable surface, in a multi-stand mill, with a Water base lubricant, may be commercially practiced by employing the methods herein described, particularly the methods described in connection with the final stand rolling.

In the rolling of these and other aluminum sheet products as described, it has been found possible to obtain sheet substantially free from Water stain or the tendency to water stain. Substantially removing rolling lubricant emulsion from the edges and at least the top surface of the strip, as by blowing air across the sheet and exhausting the blown air and moisture, produces strip substantially free of water, but with an oily lubricant remaining on its surfaces.

The practices described have permitted the continuous cold rolling of aluminum sheet in strip form, in the presence of an oil-in-water emulsion, which st-rip has both substantially uniform surfaces and surfaces substantially free from water stain or the tendency to water stain. They further permit achievement of the economic advantages of employing a backed up (e.g. 4-high)' type of mill stand to obtain substantialreductions per stand (per mill stand pass), and greater tota-l reductions, in a continuous, high speed rolling practice. The products rolled have been successfully used as sheet stock for aluminum can bodies and ends, and in other aluminum sheet applications.

What is claimed is:

1. In the continuous cold rolling of aluminum strip in a multi-stand rolling mill, the improvement comprising the following steps in combination:

employing an oil-in-water emulsion as both the coolant and the source of oily lubricant for the rolls and strip, spraying the emulsion onto the strip and the rolls at the entry side of each mill stand, also applying the emulsion in an amount providing a substantially uniform coating upon at least the top surface of the strip exiting from the mill stand immediately preceding the final mill stand, at a location nearer said preceding than said final mil-l stand, thus applying a substantially uniform amount of oily lubricant directly upon said surface promptly upon its leaving the preceding mill stand, and directing blown air across at least the edges and top surface of the strip exiting from the final mill stand in directions tending to remove emulsion therefrom so that the strip is substantially free of emulsion except for residual oily lubricant on its surfaces,

whereby aluminum strip is produced by continuous, multi-stand, cold rolling, in the presence of a cooling :and lubricating oil-in-water emulsion, which strip is characterized by having substantially uniform, smooth surfaces from the standpoint of surface irregularities, which surfaces are substantially free from water stain or the tendency to water stain by reason of retained water.

2. In the method of claim 1, rolling strip at least percent of the thickness of which is an aluminum base alloy containing 2 to 5 percent magnesium as the principal alloying constituent.

3. In the method of claim 1, rolling a two-side clad strip at least 90 percent of the thickness of which is an aluminum base alloy core containing 2 to 5 percent magnesium as the principal alloying constituent, the cladding metal layers each being selected from the group consisting of aluminum and aluminum alloys free of more than 0.05 percent magnesium and each constituting at least 2 percent of the strip thickness.

4. In the continuous cold rolling of aluminum strip in a multi-stand rolling mill, the improvement comprising the following steps in combination:

employing a continuous mill of at least four mill stands, making a total reduction in strip thickness in said mill of more than 65 percent to produce strip of a thickness between .006 and .050 inch,

employing an oil-in-water emulsion as both the coolant and the source of oily lubricant for the rolls and strip,

spraying the emulsion onto the top and bottom surfaces of the strip and the top and bottom surfaces of at least the work rolls at the entry side of each mill stand, also spraying the emulsion in an amount providing a substantially uniform spray coating pattern upon the top and bottom surfaces of the strip exiting from the mill stand immediately preceding the final mill stand,

at locations nearer said preceding than said final mill stand, thus applying substantially uniform amounts of oily lubricant directly upon said surfaces promptly upon its leaving the preceding mill stand, and directing blown air across the edges and top and bottom surfaces of the strip exiting from the final mill stand in directions tending to remove emulsion therefrom,

and collecting and withdrawing air blow across the strip, together with emulsion and water entrained therewith, so that the strip is substantially free of emulsion except for residual oily lubricant on its surfaces,

whereby aluminum strip between .006 and .050 inch thick is produced by continuous, multi-stand, cold rolling, in the presence of a cooling and lubricating oildn-water emulsion, which strip is characterized by having substantially uniform, smooth surfaces from the standpoint :of surface irregularities, which surfaces are substantially free from water stain or the tendency to water stain by reason of retained water.

5. In the method of claim 4,

employing mill stands having work rolls supported by backing rolls, and

making a total reduction in strip thickness in the mill of more than 85 percent to produce strip of a thickness between .006 and .016 inch.

6. In the cold rolling of aluminum strip wherein an oilin-water emulsion is employed as both the coolant and the source of oily lubricant for the rolls and strip, the improvement comprising the following steps in combination:

substantially removing emulsion from at least the edges and top surface of the strip exiting firom the rolls by directing blown air across such edges and surface in directions tending to remove emulsion therefrom, and collecting and withdrawing the blown air, together with emulsion and water entrained therewith, whereby the strip is substantially free of emulsion except for residual oily lubricant on its surfaces.

References Cited by the Examiner UNITED STATES PATENTS MICHAEL V. BRINDISI, Primary Examiner. 

1. IN THE CONTINOUS COLD ROLLING OF ALUMINUM STRIP IN A MULTI-STAND ROLLING MILL, THE IMPROVEMENT COMPRISING THE FOLLOWING STEPS IN COMBINATION. EMPLOYING AN OIL-IN-WATER EMULSION AS BOTH THE COOLANT AND THE SOURCE OF OILY LUBRICANT FOR THE ROLLS AND STRIP, SPRAYING THE EMULSION ONTO THE STRIP AND THE ROLLS AT THE ENTRY SIDE OF EACH MILL STAND ALSO APPLYING THE EMULSION IN AN AMOUNT PROVIDING A SUBSTANTIALLY UNIFORM COATING UPON AT LEAST THE TOP SURFACE OF THE STRIP EXITING FROM THE MILL STAND IMMEDIATELY PRECEDINNG THE FINAL MILL STAND, AT A LOCATION NEARER SAID PRECEDING THAN FINAL MILL STAND, THUS APPLYING A SUBSTANTUALLY UNIFORM AMOUNT OF OILY LUBRICANT DIRECTLY UPON SAID SURFACE PROMPTLY UPON ITS LEAVING THE PRECEDING MILL STAND, AND DIRECTING BLOWN AIR ACROSS AT LEAST THE EDGES AND TOP SURFACE OF THE STRIP EXITING FROM THE FINAL MILL FINAL STAND IN DIRECTIONS TENDING TO REMOVE EMULSION THEREFROM SO THAT THE STRIP IS SUBSTANTIALLY FREE OF EMULSION EXCEPT FOR RESIDUAL OILY LUBRICANT ON ITS SURFACES, WHEREBY ALUMINUM STRIP IS PRODUCED BY CONTINNOUS, MULTI-STAND, COLD ROLLING, IN THE PRESENCE OF A COOLING AND LUBRICATING OIL-IN-WATER EMULSION WHICH STRIP IS CHARACTERIZED BY HAVING SUBTANTIALLY UNIFORM, SMOOTH SURFACES FROM THE STANDPOINT OF SURFACE IRREGULARITIES, WHICH SURFACES ARE SUBSTANTIALLY FREE FROM WATER STAIN OR THE TENDANCY TO WATER STAIN BY REASON OF RETAINED WATER. 